[입시] 뇌인지과학 세미나 안내

일 시: 2012년 8월 31일 (금) 16:00

장 소: 인문대 신양학술정보관(4동) 3층 국제회의실(302호)

초 록: Intercepting momentarily-invisible moving objects requires internal-generated estimations of target trajectory. We have found that the parabigeminal nucleus (PBN) encodes such estimations, combining sensory representations of target location, extrapolated positions of briefly obscured targets, and eye-position information. When cats visually track moving targets, the activity of PBN cells encodes the distance between the direction of gaze and the target. If a target with a predictable trajectory is briefly turned off, PBN activity continues to encode target position as the unseen target moves along its (virtual) trajectory. PBN encoding of target position also takes into account changes in eye position resulting from saccades, even without visual feedback. PBN activity is specific to the intended target of a saccade, and is predictive of which target will be chosen if two are offered. The PBN is heavily interconnected with the superior colliculus (SC), the main midbrain generator of saccadic eye movements. SC cells, which are far more heterogeneous in properties than PBN cells, also encode extrapolated position of unseen targets, but less commonly and with poorer accuracy than PBN cells. Our results suggest that the PBN-SC circuit functions to extract and refine target position to provide the SC with accurate information for directing saccades, particular for saccades directed toward the extrapolated positions of momentarily unseen targets moving along predictable trajectories.